Update structopt dependency to 0.3.21

This change updates the structopt crate to version 0.3.21. We need this
version as it fixes a compilation error [0] when using the
external_subcommand enum variant annotation provided by the crate with
certain versions of Rust.

[0]: https://github.com/TeXitoi/structopt/issues/447

1 files changed, 1 insertions, 1 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 1af4f2f..c2d1d34 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -61,7 +61,7 @@ version = "1.0"
 features = ["derive"]
 
 [dependencies.structopt]
-version = "0.3.17"
+version = "0.3.21"
 default-features = false
 
 [dependencies.termion]